Urban Dictionary: Weak Sister

1. A weak or undependable member of a group. 2. A person regarded as timid or indecisive.

Jim's a fuckin' weak sister, he couldn't decide whether to shit or go blind.

by zboss June 10, 2007

The lesser of two twins, regardless of sex. There is always a dominant twin.

Jesse may be a superior athlete but he is totally the Weak Sister.